Pipeline pressure isolation systems and devices

ABSTRACT

A pressure isolation device for a pipeline system is described. The pressure isolation device changes from an open position to a closed position when the pressure of a fluid flowing through the device exceeds a predetermined threshold pressure. In some embodiments, the pressure isolation device comprises a housing having an internal chamber, a main inlet, and a main outlet. An elongated member is disposed within the internal chamber between the main inlet and main outlet, and is biased towards the open position. As fluid pressure increases, the elongated member is pushed to the closed position and a portion of the elongated member blocks the fluid pathway from the main inlet to the main outlet. The pressure isolation device provides a simple mechanical solution to protecting and isolating downstream pipeline components from over-pressurization.

This application is a continuation-in-part of U.S. patent application Ser. No. 13/658,682, filed on Oct. 23, 2012. This and all other referenced extrinsic materials are incorporated herein by reference in their entirety. Where a definition or use of a term in a reference that is incorporated by reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein is deemed to be controlling.

FIELD OF THE INVENTION

The field of the invention is valves, more specifically, devices and systems for isolating pressure build-up in pipelines.

BACKGROUND

Pipelines for transporting oil, natural gas, water, and other important resources, are used globally and are an important part of commerce and infrastructure. Such pipeline systems generally rely on pumps and/or compressors to move fluid through the pipeline. If a blockage occurs downstream from a compressor, pressure will build-up in the pipeline and can lead to cracking, breakages, leaks, and environmental damage.

Several approaches to preventing pipeline pressure build-ups and breakages are known. One known solution is to include pressure safety valves (“PSV”). PSV's are configured to automatically open up at a predetermined pressure threshold, thus relieving (e.g., bleeding) pipeline pressure into the surrounding environment. PSV devices are considerably economical to manufacture and install, however, the cost of environmental damage and lost product (e.g., oil, water, natural gas, etc) is significant. Flares can be used to reduce damage to the environment.

Another approach to preventing pipeline overpressure is high integrity pressure protection systems (“HIPPS”). A typical HIPPS includes sensors for monitoring pipeline pressures and a control system for automatically shutting off the source of the overpressure (e.g., shutting off the compressor or closing a valve) when pipeline pressure passes a threshold value. HIPPS, however, have several drawbacks. First, the sensors and control system add significant costs to the pipeline. Second, sensors and control system components can degrade over time and are susceptible to weather damage.

Yet another approach to preventing pipeline breakage from pressure build-up is to use pipeline designs (e.g., diameters, thickness, joining processes, materials, etc.) that can handle the maximum pressure output of the compressor. However, this approach is economically impractical for long pipeline routes (e.g., oil transportation pipelines).

Examples of other devices and methods of preventing system overpressure can be found in GB2431485, U.S. Pat. No. 4,167,194, U.S. Pat. No. 5,269,347, U.S. Pat. No. 6,164,927, U.S. Pat. No. 7,344,127. Unfortunately, the devices and methods described in these references also suffer from similar drawbacks as the previously mentioned approaches.

These and all other extrinsic materials discussed herein are incorporated by reference in their entirety. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.

Thus, there is still a need for improved devices, systems, and methods for pressure isolation and/or overpressure prevention.

SUMMARY OF THE INVENTION

The inventive subject matter provides apparatus, systems and methods in which pipeline segments can be isolated from one another using pressure isolation devices (e.g., shutoff valves) to prevent pressure build-up throughout the entire pipeline. The pressure isolation device is configured to automatically switch to a shutoff state as a function of pipeline pressure, without the need for human input and without the need for electrical or hydraulic systems.

In one aspect of some embodiments, a pressure isolation device includes a housing having an internal chamber, a main inlet and a main outlet. The main inlet and main outlet can be coupled with a first pipe segment and a second pipe segment, respectively. The internal chamber includes an elongated member disposed within the internal chamber. The elongated member is movable (e.g., slidable or rotatable) between a first position (e.g., an open position) and a second position (e.g., a closed position or a shutoff position). The elongated member is biased towards the first position (e.g., via a spring, pressured chamber, or some other suitable biasing member).

The elongated member comprises a piston (e.g., a large diameter section) that fluidly decouples two portions of the internal chamber. When the pressure isolation device is in the open position, the main inlet is fluidly coupled with the main outlet. As the pressure of the fluid flowing through the pressure isolation device increases, the pressure against the piston will eventually overcome the elongated member's bias for the open position, and push the elongated member into the second position (e.g., the shutoff position). In the shutoff position, the main inlet is fluidly decoupled from the main outlet.

In some embodiments, the shutoff position is achieved when a plug on the elongated member is moved into a position that blocks fluid flow from the main inlet to the main outlet. In other embodiments, the shutoff position is achieved when a portion of the fluid pathway from the main inlet to the main outlet (e.g., a conduit or valve) is moved into a blocked position.

Various objects, features, aspects, and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 a is a schematic of a pipeline system with a pressure isolation device.

FIG. 1 b is a schematic of the pipeline system of FIG. 1A with a blockage.

FIG. 2 is a perspective view of one embodiment of a pressure isolation device.

FIG. 3 a is a cross sectional view of the pressure isolation device of FIG. 2.

FIG. 3 b is a cross sectional view of the housing of the pressure isolation device of FIG. 2.

FIG. 3 c is a perspective view of the elongated member of the pressure isolation device of FIG. 2.

FIG. 3 d is a close-up of FIG. 3 a.

FIG. 3 e is a close-up of the elongated member in FIG. 3 d.

FIG. 3 f is a close-up of the pressure isolation device of FIG. 3 a, showing the elongated member in a transitional state.

FIG. 3 g is a side view of the elongated member section shown in FIG. 3 e.

FIG. 4 a is a cross sectional view of the pressure isolation device of FIG. 2 in an open position.

FIG. 4 b is a cross sectional view of the pressure isolation device of FIG. 2 in a closed position.

FIG. 5 is a cross sectional view of another embodiment of a pressure isolation device.

FIG. 6 is a perspective view of another embodiment of an elongated member for a pressure isolation device.

FIGS. 7 a and 7 b are perspective and cross sectional views, respectively, of an elongated member and a housing for another embodiment of a pressure isolation device.

FIGS. 8 a and 8 b are perspective and cross sectional views, respectively, of an elongated member and a housing for another embodiment of a pressure isolation device.

FIG. 9 is a perspective view of yet another embodiment of an elongated member.

FIG. 10 is a cross sectional view of a spring-less pressure isolation device.

FIG. 11 is a cross sectional view of another embodiment of a spring-less pressure isolation device.

FIGS. 12 a and 12 b are cross sectional views of another embodiment of a pressure isolation device, in an open and closed position, respectively.

FIGS. 13 a and 13 b are cross sectional views of another embodiment of a pressure isolation device, in an open and closed position, respectively.

FIGS. 14 a and 14 b are cross sectional views of another embodiment of a pressure isolation device, in an open and closed position, respectively.

FIGS. 15 a and 15 b are cross sectional views of another embodiment of a pressure isolation device, in an open and closed position, respectively.

DETAILED DESCRIPTION

The following discussion provides many example embodiments of the inventive subject matter. Although each embodiment represents a single combination of inventive elements, the inventive subject matter is considered to include all possible combinations of the disclosed elements. Thus if one embodiment comprises elements A, B, and C, and a second embodiment comprises elements B and D, then the inventive subject matter is also considered to include other remaining combinations of A, B, C, or D, even if not explicitly disclosed.

One should appreciate that the disclosed devices provide many advantageous technical effects including a pressure isolation system that is cost effective and low maintenance.

FIG. 1 a shows a pipeline system 100 for transporting a fluid. System 100 comprises a first pipe segment 101, a pump 102, a second pipe segment 103, a pressure isolation device 104, and a third pipe segment 105. Pump 102 creates a pressure difference that pulls the fluid from pipe segment 101 into pump 102 and pushes the fluid into pipe segment 103. The fluid flows through pressure isolation device 104 and into pipe segment 105.

FIG. 1 b shows pipeline system 100 when a blockage 106 occurs downstream of pressure isolation device 104. Blockage 106 prevents fluid from flowing further down stream into pipe segment 107 and causes a pressure buildup between blockage 106 and pump 102. Once the pressure builds up to a predetermined threshold, pressure isolation device 104 changes from an open position to a closed position (e.g., shutoff position). In the closed position, pressure isolation device 104 prevents fluid from flowing into pipe segment 105 and isolates downstream segments and components from the pressure buildup.

FIG. 2 shows pressure isolation device 104 apart from system 100. Pressure isolation device 104 comprises a housing 110 having vents 111. Housing 110 also has a first flanged pipe segment 112 (i.e., a main inlet) and a second flanged pipe segment 113 (i.e., a main outlet) that couple with pipe segments 103 and 105, respectively. The flanges of segments 112 and 113 are screwed to flanges on segments 103 and 105 (not shown) to provide a secure and fluid connection. Couplings for pipe segments are well known and the inventive subject matter is not limited to any particular coupling. In alternative embodiments, device 104 could couple with pipe segments 103 and 105 using threaded engagements, male-female engagements, snap fittings, clamps, adhesives, welds, or any other coupling suitable for providing a secure and fluid connection under the required specifications (e.g., temperature, pressure, corrosivity, etc.).

FIG. 3 a shows a cross sectional view of pressure isolation device 104. Disposed within housing 110 of device 104 is an elongated member 120 and a spring 118. Elongated member 120 is slidably disposed within housing 110 and is biased downwards in a first position (i.e., an open position) by spring 118.

FIG. 3 b shows housing 110 with elongated member 120 and spring 118 removed. Housing 110 has a first internal chamber 131, a second internal chamber 133, and a third internal chamber 135. Chambers 131 and 133 are separated by an opening 132 and chambers 133 and 135 are separated by an opening 134.

First chamber 131 has a first opening 141, second opening 142, and a third opening 143. Openings 141 and 142 operate as first and second inlets, respectively. Opening 143 operates as a first outlet.

Housing 110 can be made of any material suitable for withstanding the conditions of the pipeline application (e.g., temperature, pressure, corrosivity, etc.). Examples of contemplated materials include, but are not limited to, metal alloys, polymers, composites, and ceramics.

FIG. 3 c shows elongated member 120 apart from pressure isolation device 104. Elongated member 120 has a piston 121 at one of its ends. Piston 121 has a through hole 122. Elongated member 120 also has a catch 123 and a catch 124. Catch 123 has two frustoconical plugs (i.e., trapezoidal cross sections) on each side for engaging openings 132 and 134. Openings 132 and 134 are tapered such that they engage the plugs of catch 123 to provide a substantial seal (i.e., openings 132 and 134 have trapezoidal cross sections that are concentric with cross sectional portions of the plugs on catch 123), and more preferably a complete seal. As used herein, “substantial seal” and “fluidly decoupling” mean fluid flow is greatly inhibited, although not necessarily completely eliminated, under a given set of conditions (e.g., pressure, temperature viscosity, fluid flow type, etc.). As used herein, “concentric” means to have a common center or common shape.

When elongated member 120 is disposed in housing 110, piston 121 is disposed in internal chamber 131, catch 123 is disposed in internal chamber 133, and catch 124 is disposed in internal chamber 135. Elongated member 120 has a length that is shorter than the internal length of housing 110, which allows elongated member 120 to slide within housing 110. Elongated member 120 is appropriately sized and dimensioned to slide a specific distance between a closed position and an open position within housing 110.

Piston 121 is appropriately sized and dimensioned in relation to internal chamber 131 such that, when elongated member 120 is in the open position, fluid flows from pipe segment 112 to pipe segment 113 through opening 122. However, when elongated member 120 is in the closed position, the size and dimension of piston 121 in relation to internal chamber 131 blocks flow from segment 112 to segment 113.

Internal chamber 133 has a sealing surface 133 a that mates with the circumferential surface of catch 123 in such a manner that a fluid seal is maintained while elongated member 120 slides between open and closed positions. Slidable sealing surfaces are known and could comprise any material and configuration suitable for providing a sliding seal under the particular conditions of pipeline system 100. Metals, polymers, fiber-reinforced composites, ceramics, and elastomers are examples of materials that may be used to provide a sliding sealing surface.

Pipeline conditions will vary depending on numerous factors such as the characteristics of the fluid being transported (e.g., viscosity, density, corrosivity), the capacity of the pump (e.g., maximum pressure output), elevation changes in the pipeline, and environmental temperatures and conditions (e.g., earthquakes). The inventive concepts described herein can be applied to any set of pipeline conditions and any fluid. Contemplated fluids include, but are not limited to: water, crude oil, natural gas (liquid or vapor), and absorbent slurries for treating flue gas.

The various structural features of elongated member 120 and housing 110 will now be explained in relation to the operation of pressure isolation device 104.

FIG. 4 a shows pressure isolation device 104 in a first position, referred to as the open position. In the open position, through hole 122 on piston 121 of elongated member 120 is aligned with opening 142 and 143, allowing a fluid to flow from pipe segment 112 to 113 (see flow path 149). Elongated member 120 is sized and dimensioned such that opening 141 is not directly coupled with opening 143 (e.g., the pathway from opening 141 to opening 143 via chamber 131 is blocked by piston 121) when elongated member 120 is in the open position. Spring 118 engages catch 124, pushing elongated member downward until the end of piston 121 contacts the interior bottom surface of internal chamber 131. In addition, the lower plug of catch 123 contacts opening 132 to provide a seal that fluidly decouples internal chamber 131 from internal chamber 133. Catch 123 and opening 132 have complementary (i.e., concentric) frustoconical surfaces to provide a gradual sealing engagement as elongated member 120 is forced downward by spring 118.

As the pressure in pipeline system 100 increases due to blockage 106 downstream of pressure isolation device 104, the pipeline pressure upstream of blockage 106 increases. Once the pipeline pressure reaches a predetermined threshold, the pipeline pressure will surpass the downward force provided by spring 118 and the weight of elongated member 120. As a result, elongated member 120 will be pushed upward into the second position, referred to as the closed position or shutoff position (see FIG. 4 b).

The force required to surpass the force of spring 118 and the weight of elongated member 120 can be approximated as follows: F _(u) =P ₁ A where F_(u) is the upward force provided by the pipeline pressure, P₁ is the pipeline pressure, and A is the effective area (i.e., the area upon which the pipeline pressure acts to move elongated member 120 upward). FIG. 3 d shows a close-up view of elongated member 120 being acted upon by pipeline pressure P₁. The effective area (A) is a portion of the lower frustoconical plug of catch 123 that is exposed to P₁, which can be approximated as a planar two-dimensional surface area, as follows:

$A = {\frac{\pi}{4}\left( {D_{2} - D_{1}} \right)^{2}}$ where D₁ and D₂ are the diameters of two cross sections of elongated member 120 as shown in FIGS. 3 e and 3 g. More specifically, D₂ is the cross sectional diameter of elongated member 120 at the first point where the lower frustoconical plug of catch 123 is exposed to P₁.

Those of ordinary skill in the art will appreciate that the effective area can also be approximated by taking into account the three dimensional geometry of elongated member 120. Those of ordinary skill will also appreciate that alternative embodiments of elongated member 120 that have different geometries, will likewise have different equations for approximating the effective area and the force provided by P₁.

When the upward force (F_(u)) provided by the pipeline pressure (P₁ surpasses the downward forces (e.g., force of spring 118, weight of elongated member 120, friction between moving components, etc.), elongated member 120 will begin to move upward. As a result, the pipeline fluid will flow into internal chamber 133 and the size of the effective area will change, as shown in FIG. 3 f. The new effective area can be approximated as a planar two-dimensional area, as follows:

$A = {\frac{\pi}{4}\left( {D_{3} - D_{1}} \right)^{2}}$ where D₁ and D₃ are the diameters of two cross sections of elongated member 120 as shown in FIGS. 3 e and 3 g. As long as the upward force (F_(u)) remains greater than the downward force, elongated member 120 will move upward and into the shutoff position.

In alternative embodiments, spring 118 can provide a variable force rather than a constant force, in order to match the variation in upward force (e.g., the variation in effective area). For example, since the effective area increases and thus the upward force increases as elongated member 120 moves upward, spring 118 could be configured to provide a downward force that increases at a variable rate as spring 118 is compressed. In embodiments in which the downward force is provided by pressurizing internal chamber 135 rather than by a spring, a variable downward pressure can be provided by (i) including a constituent in the pressurized gas that changes phases (e.g., gas-to-liquid) during compression, (ii) applying an external heat exchanger to internal chamber 135, or (iii) using any other known method.

FIG. 4 b shows pressure isolation device 104 in the shutoff position. In this position, through hole 122 is no longer aligned with openings 142 and 143 and fluid flow path 149 is now blocked. However, opening 141 remains fluidly coupled with internal chamber 131 and the pressure of internal chamber 131 is equal to the upstream pipeline pressure. Catch 123 is in contact with opening 134, preventing elongated member 120 from sliding any further upwards. The contact also provides a seal that fluidly decouples internal chamber 133 from internal chamber 135 and contains fluid within the pipeline (i.e., there are substantially no emissions from device 104).

Housing 110 also has a vent 111 (see FIG. 3 a). Vent 111 maintains the pressure within inner chamber 135 equal to atmospheric pressure. In the event that the seal between catch 123 and sealing surface 133 a fails, vent 111 prevents pressure from building up in inner chamber 135 by letting fluid flow out of pressure isolation device 104. Vent 111 helps to prevent inner chamber 135 from structural damage that can be caused by over-pressurization.

In the shutoff position, pressure isolation device 104 isolates downstream pipe segment 105 from being exposed to pressures above the predetermined threshold. Pipeline components upstream of device 104 (e.g., pump 102, pipe segment 103) are configured to withstand the maximum pressure output of pump 102. For example, pipe segment 112 is made of a higher strength material and has a greater thickness than pipe segment 113, since pipe segment 112 may be exposed to higher pressures than pipe segment 113. Once blockage 106 is removed, pressure isolation device 104 can be returned to the open position to resume fluid flow, either manually or automatically (i.e., by letting the upstream pressure fall below the threshold pressure).

In some applications, normal pipeline operating pressure is 2400 psig and the pump is a centrifugal compressor with a maximum pressure output of 3000 psig (i.e., deadhead pressure). The pressure isolation device is configured to switch from the open position to the closed position at about 2400 psig (e.g., the spring constant, spring length, weight/shape of the elongated member, design of the housing, and other relevant parameters are all specifically selected to provide a threshold pressure of about 2400 psig). As such, pipeline segments and components located downstream of the pressure isolation device are designed to withstand up to about 2500 psig whereas upstream components are designed to withstand up to about 3100 pressure.

Those of ordinary skill in the art will appreciate that numerous variations of device 104 can be employed without departing from the general inventive subject matter. For example, FIG. 5 shows a pressure isolation device 504. Device 504 is similar to device 104 except that device 504 lacks a first flanged pipe segment 112 and a second flanged pipe segment 113. Instead, device 504 is coupled with a pipeline system via a welding between an outer surface of housing 510 and an opening in a pipe segment of a pipeline system (not shown).

Device 504 also differs from device 104 in that device 504 has a pipe segmented vent 511. Vent 511 can be used to connect another pipe segment for the purposes of receiving pipeline fluid in the event that the seal between elongated member 520 and housing 510 fails.

FIG. 6 shows an alternative embodiment for an elongated member. Elongated member 620 is similar to elongated member 120 except that elongated member 620 has a tapered piston 621. Tapered piston 621 is shaped to engage a tapered internal chamber (not shown) of a housing for a pressure isolation device.

FIGS. 7 a and 7 b show another alternative embodiment of a pressure isolation device. FIG. 7 a shows an elongated member 720, which has a catch 723. Unlike catch 123 of elongated member 120, catch 723 is disc shaped and does not have frustoconical sides (i.e., plugs). Openings 732 and 734 of housing 710 are straight rather than tapered. The flat sides of openings 732 and 734 engage the flat sides of catch 723 to provide a fluid seal.

FIGS. 8 a and 8 b show yet another embodiment of a pressure isolation device. FIG. 8 a shows an elongated member 820 having a spherical catch 823. Internal chamber 833 of housing 810 has an elongated spherical shape that allows catch 823 to sealably slide within chamber 833. Catch 823 has a sliding and sealing surface 827 that assists in maintaining a fluid seal between catch 823 and internal chamber 833 while elongated member 820 is in motion. The upper and lower spherical surfaces of catch 823 are concentric with openings 834 and 832, respectively, and mate together to provide a fluid seal when elongated member 820 is in the closed and open positions.

FIG. 9 shows an elongated member 920, which has a piston portion 921, a first catch portion 923, and a second catch portion 924. These three portions have local maximum diameters and are separated from one another by small diameter portions 922 and 925. Since the change in diameter of elongated member 920 is gradual, the exact start and end point of piston 921, catch 923, and catch 924 is difficult to determine. Nonetheless, each portion of elongated member 920 has sufficient structural features to perform their required function. For example, catch 924 is large enough to engage a spring to provide elongated member 920 with a force such that it is biased in an open position within a housing of a pressure isolation device (not shown). Catch 923 is large enough to slidably and sealably engage an internal chamber of a housing. Piston 921 is large enough to fluidly decouple a first inlet from a first outlet, and also fluidly couple a second inlet with the first outlet.

FIG. 10 shows a spring-less embodiment of a pressure isolation device. Pressure isolation device 1004 has an elongated member 1020 that has a weighted portion 1025. Device 1004 is attached to a pipeline system (not shown) and oriented in a field of gravity such that the weight and shape of elongated member 1020 (i.e., force and area) provides sufficient pressure to define the threshold pressure of the pipeline system. When a blockage occurs in the pipeline system and the pressure passes this threshold, the weight of elongated member 1020 is overcome and elongated member 1020 is pushed upward until weighted portion 1025 contacts the top of internal chamber 1035. The specific distance traveled by elongated member 1020 between the open and closed position is determined by the difference in lengths of elongated member 1020 and the internal chambers of housing 1010. Internal chamber 1035 preferably has a sliding sealing surface 1035 a that is at least as long as the distance traveled by elongated member 1020. In addition, the distanced traveled by elongated member 1020 is at least as long as the diameter of the fluid path flow (in this case, the diameter of opening 1042 and through hole 1022).

Unlike the housings of previously described pressure isolation devices, housing 1010 has only two internal chambers (i.e., internal chamber 1031 and internal chamber 1035).

FIG. 11 shows another spring-less pressure isolation device. Pressure isolation device 1104 has a housing 1110 and an elongated member 1120. Housing 1110 has only one internal chamber, namely, internal chamber 1131. Elongated member 1120 has a first piston 1121 and a second piston 1123. First piston 1121 functions in a manner similar to piston 121 of pressure isolation device 104 (see FIGS. 4 a and 4 b). Second piston 1123, however, differs from catch 123 and 723 in that piston 1123 does not sealably engage an internal chamber opening. Instead, piston 1123 slides freely from open to closed positions. At least a portion of the surfaces of internal chamber 1131 includes a sealing surface 1131 a that slidably and sealably engages second piston 1123. Second piston 1123 divides internal chamber 1131 into two fluidly decoupled sub-chambers; a top sub-chamber and a sub-bottom chamber. The top sub-chamber has been pressurized with a gas such as air. The pressure of the top sub-chamber (TCP) in combination with the weight and shape of elongated member 1120 defines the predetermined threshold pressure. When a blockage in a pipeline occurs and the pipeline pressure passes the threshold pressure, elongated member 1120 is forced upward a specific distance until pipeline flow through pressure isolation device 1104 is blocked. The distance traveled by elongated member 1120 is defined by the difference in the length of elongated member 1120 and internal chamber 1131.

In yet other embodiments, the pressure isolation devices can restrict fluid flow via means other than a through hole on the piston at the end of the elongated member. For example, FIG. 12 a shows a pressure isolation device 1200 in an open position. Device 1200 comprises a main inlet 1212 and a main outlet 1213. In the open position, main inlet 1212 is fluidly coupled with main outlet 1213 (e.g., hole 1222 is unplugged as shown by flow path 1249). In this open position, elongated member 1220 is at a rest position and plug 1221 is positioned in such a manner as to allow the fluid to flow through hole 1222.

Similar to the various embodiments described above, pressure isolation device 1200 blocks the flow of fluid when a pressure threshold is reached. The increase in pressure can be due to a blockage downstream of pressure isolation device 1200. Once the pipeline pressure reaches a predetermined value, the pipeline pressure will surpass the pressure threshold (e.g., spring bias, weight bias, pressured chamber, etc) and push elongated member 1220 upward. Elongated member 1220 has a piston 1224 that is sized and dimensioned to create a seal with the circumferential surface of the inside walls of housing 1210, thus fluidly decoupling a lower portion and an upper portion of the internal space within housing 1210. As such, once the pressure threshold is reached, piston 1224 is pushed upward and elongated member 1220 moves to a second position (i.e., closed position), as shown in FIG. 12 b. In this closed position, fluid cannot flow from main inlet 1212 to main outlet 1213 since flow path 1249 is blocked by plug 1221 at hole 1222.

It should also be noted that elongated member 1220 passes through an inner wall of housing 1210 at a seal 1223. Seal 1223 allows elongated member 1220 to slide between the open and closed positions, but prevents the leakage of pressure (e.g., fluid) from main inlet 1212 to main outlet 1213 when in the closed position. Seal 1223 can be manufactured from various types of materials so long as the material can functionally create a seal between elongated member 1220 and a hole in the inner wall of housing 1210.

One advantage of the embodiment illustrated in FIGS. 12 a and 12 b is that pressure isolation device 1200 can handle a “dirty” fluid since the internal components of pressure isolation device 1200 are less susceptible to clogging caused by dirt accumulation. For example, the movement of plug 1221 within hole 1222 helps to break up any accumulated solid material.

FIG. 13 a shows a pressure isolation device 1300 that uses an elongated member 1320 and plug 1321. Device 1300 is similar to device 1200 in many aspects. However, device 1300 differs from device 1200 in that the movement of elongated member 1320 is transmitted to plug 1321 through a U-bend.

Device 1300 has a fluid flow path 1349 that travels from main inlet 1312 to main outlet 1313 via a hole 1322. Once a pre-determined threshold value is reached, the pipeline pressure will surpass the pressure bias and elongated member 1320 will move upward and into a closed position, as shown in FIG. 13 b. The pressure bias can be provided by any of the means previously described (e.g., spring bias, weight bias, pressured chamber, etc), by combinations thereof, or by any other known mechanism for providing a biasing force.

In the closed position, fluid flow path 1349 is blocked due to the blockage of hole 1322 by plug 1321. Plug 1221 has a frustoconical shape (e.g., slanted/tapered sides, trapezoidal cross section) that mates with the tapered sides of hole 1322. As the pipeline pressure increases, plug 1221 is wedged further into hole 1322 and provides an improved seal.

Unlike device 1200, device 1300 obviates the need for a seal 1223 since elongated member 1320 does not pass through a hole of the inner wall of housing 1310.

FIG. 14 a shows a pressure isolation device 1400 that has an elongated member 1420. Elongated member 1420 includes a piston 1424, and a plug 1421. Plug 1421 is connected to piston 1424 via a lever 1460 (e.g., linkage, arm, etc.). Lever 1460 is rotatably coupled with elongated member 1420 at pivot point 1450. Lever 1460 is also rotatably coupled with plug 1421 via pivot point 1452. Lever 1460 is also coupled with inner wall 1477 via pivot point 1451.

Once a pre-determined pressure threshold value is reached, pressure isolation device 1400 moves to its closed position as shown in FIG. 14 b. As the elongated member 1420 moves upward due to the pipeline pressure, the left end of lever 1460 (e.g., pivot point 1450) also moves upward. At the same time, the right end of lever 1460 (e.g., pivot point 1452) moves downward and pushes plug 1421 into hole 1422, which effectively blocks fluid flow pathway 1449. Pivot point 1452 allows plug 1421 to change from an acute angle with respect to lever 1460, as shown in FIG. 14 a, to an obtuse angle, as shown in FIG. 14 b. Similarly, pivot point 1450 allows the angle between lever 1460 and elongated member 1420 to change as elongated member 1420 transitions from an open position to a closed position.

In alternative embodiments, lever 1460 and plug 1421 can be formed of one piece, which eliminates the need for pivot point 1452. The angle between lever 1460 and plug 1421 can be configured such that plug 1421 mates with hole 1422 in the closed position (e.g., FIG. 14 b). In addition, the size, shape, and orientation of both plug 1421 and the opening of inner wall 1477 can be configured to account for the lack of rotation of plug 1421 with respect to lever 1460.

In yet other alternative embodiments pivot point 1450 can be at some point along elongated member 1450 and lever 1460 other than at their ends. In addition, pivot point 1451 can be located at a point other than the center of lever 1460 and lever 1460 could even have an irregular shape to meet the requirements of a specific application (e.g., space limitations, weight limitations, etc.).

In another aspect, it is contemplated that the pressure isolation devices can control fluid flow with the use of a rotating ball valve rather than a plug. In such embodiments, the fluid pathway itself is being moved into a blocked position rather than moving a plug into a blocking position. FIG. 15 a shows pressure isolation device 1500 comprising an elongated member 1520 disposed in a housing 1510. Elongated member 1520 is biased towards a downward (i.e., open) position via a spring or some other biasing means (not shown). Elongated member 1520 has a piston 1524 in sliding and sealing contact with an inner surface of housing 1510 and serves to fluidly decouple the lower portion of the internal chamber of housing 1510 with the upper portion. The bottom end of elongated member 1520 is connected to a lever 1560 at pivot point 1550. Lever 1560 is also attached to a ball valve 1521 disposed within the spherical portion of inner wall 1577. Lever 1560 causes ball valve 1521 to rotate within the spherical portion of inner wall 1577 when elongated member 1520 shifts upward. Lever 1560 attaches to ball valve 1521 through an opening in the spherical portion of inner wall 1577.

The spherical portion of inner wall 1577 also has two additional openings 1578 that serve as an inlet and outlet for fluid pathway 1549. In the open position, as shown in FIG. 15 a, through hole 1522 of ball valve 1521 is aligned with openings 1578 and fluid pathway 1549 remains open and unobstructed.

Similar to the other embodiments described above, pressure isolation device 1500 moves into a closed position when the pre-determined threshold value is reached. FIG. 15 b shows pressure isolation device 1500 in a closed position. In this closed position, elongated member 1520 has shifted upward from the open position. When elongated member 1520 shifted upwards, ball valve 1521 was rotated within the spherical portion of inner wall 1577 via lever 1560. It should be noted that the outer surface of ball valve 1521 is in sliding sealing contact with the inner surface of the spherical portion of inner wall 1577. In the closed position, through hole 1522 is no longer aligned with openings 1578 and fluid pathway 1549 is blocked. As a result, the pipe segment connected to main outlet 1513 has been isolated from the pressure in main inlet 1512.

Although the biasing means is not shown in FIGS. 15 a and 15 b (e.g., the upper portion of device 1500 is not shown), it is contemplated that any biasing means suitable for providing a biasing force or pressure can be used (e.g., spring, weight, pressurized chamber, etc.).

Some of the advantages of the inventive pressure isolation devices will now be discussed. First, contemplated pressure isolation devices provide an automatic shutoff valve for isolating downstream pipe segments and components. The downstream segments and components are thus protected from damage that can result from over-pressurization. Second, unlike complex and expensive HIPPS, the contemplated pressure isolation devices are simple, economical, and principally rely on mechanical principles. Third, unlike PSV's, contemplated pressure isolation devices contain the fluid within the pipeline system (i.e., no emissions), thus eliminating environmental harm and fluid waste. Fourth, contemplated devices require little maintenance and testing. Fifth, the inventive pressure isolation devices are a dependable solution and do not require power, instrument air, or an actuator. Finally, these devices can be used as a backflow preventer in gas feed manifolds.

Those of skill in the art will appreciate that many other alternative embodiments can be employed without departing from the inventive concepts discussed herein. In addition, pipeline systems can include multiple pressure isolation devices with different threshold pressures to protect pipeline components with different ratings and specifications.

Unless the context dictates the contrary, all ranges set forth herein should be interpreted as being inclusive of their endpoints, and open-ended ranges should be interpreted to include commercially practical values. Similarly, all lists of values should be considered as inclusive of intermediate values unless the context indicates the contrary.

As used herein, and unless the context dictates otherwise, the term “coupled to” is intended to include both direct coupling (in which two elements that are coupled to each other contact each other) and indirect coupling (in which at least one additional element is located between the two elements). Therefore, the terms “coupled to” and “coupled with” are used synonymously.

It should be apparent to those skilled in the art that many more modifications besides those already described are possible without departing from the inventive concepts herein. The inventive subject matter, therefore, is not to be restricted except in the scope of the appended claims. Moreover, in interpreting both the specification and the claims, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms “comprises” and “comprising” should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced. Where the specification claims refers to at least one of something selected from the group consisting of A, B, C . . . and N, the text should be interpreted as requiring only one element from the group, not A plus N, or B plus N, etc. 

What is claimed is:
 1. A pressure isolation device, comprising: a housing having an internal chamber, a main inlet, a main outlet, and an inner wall between the main inlet and main outlet, wherein the inner wall includes a first opening; an elongated member disposed within the internal chamber and movable between a first position and a second position, and biased towards the first position; wherein the elongated member comprises a piston and a plug; wherein the piston is sized and dimensioned to contact a surface of the internal chamber to fluidly decouple a first portion of the internal chamber from a second portion of the internal chamber; wherein at the first position, the plug is disposed outside of the opening of the inner wall such that the opening fluidly couples the main inlet and the main outlet; and wherein at the second position, the plug is disposed in the first opening of the inner wall such that the plug fluidly decouples the main inlet from the main outlet; wherein at the second position, the main inlet is fluidly coupled with a surface of the piston and a surface of the plug; and wherein the surface plug is oriented such that a main inlet pressure acts on the surface of the plug in a direction that biases the elongated member toward the second position.
 2. The pressure isolation device of claim 1, wherein the elongated member travels a distance from the first position to the second position.
 3. The pressure isolation device of claim 2, wherein the distance is limited by a difference in length between the elongated member and the internal chamber.
 4. The pressure isolation device of claim 1, further comprising a spring coupled with an end of the elongated member and configured to bias the elongated member towards the first position.
 5. The pressure isolation device of claim 4, wherein the spring is disposed in the first portion of the internal chamber and the inner wall is disposed in the second portion of the internal chamber.
 6. The pressure isolation device of claim 1, wherein the first portion of the internal chamber is pressurized such that the elongated member is biased towards the first position.
 7. The pressure isolation device of claim 1, wherein the piston includes a seal that provides slidable sealing contact with a surface of the internal chamber to fluidly decouple the first portion from the second portion.
 8. The pressure isolation device of claim 1, wherein the entire length of the elongated member is substantially straight and the plug is disposed on an end of the elongated member.
 9. The pressure isolation device of claim 8, wherein a portion of the elongated member is disposed in, and in slidable sealing contact with, a second opening of the inner wall.
 10. The pressure isolation device of claim 1, wherein the first opening is a tapered opening.
 11. The pressure isolation device of claim 10, wherein the plug has a tapered shape that mates with the first opening.
 12. The pressure isolation device of claim 1, wherein the elongated member has a U-shaped end and the plug is disposed on the U-shaped end.
 13. The pressure isolation device of claim 1, wherein the main inlet and the main outlet each have a flange configured to couple with a pipeline flange. 